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Novel graphene-supramolecular elastomer hybrids for self-healing stretchable electronics

Periodic Reporting for period 1 - SUPRONICS (Novel graphene-supramolecular elastomer hybrids for self-healing stretchable electronics)

Reporting period: 2015-12-01 to 2017-11-30

Stretchable electronics are highly attractive in various applications including wearable medical devices. However, most of the existing conducting materials used in electronics lack either high stretchability or high conductivity, limiting their applications. This project aims to develop new materials with a good combination of stretchability and conductivity, as well as added-value self-healing ability, to help address these problems.

These new materials are expected to enhance the performance and lifetime of existing stretchable electronics whilst also facilitating the low-cost fabrication of electrical circuits.

The principal objectives of this project are as follows:
1) To prepare and characterise functionalised graphene nanosheets;
2) To synthesise and characterise self-healing elastomer-graphene nanocomposites and assess their properties; and
3) To fabricate stretchable electrical circuits using the above nanocomposites and evaluate their potential performance.
During the project period, functionalised graphene nanosheets were prepared and characterised, and a series of conductive elastomer nanocomposites were synthesised and investigated as potential stretchable electronics.

First, we prepared novel self-healing, conductive graphite-branched polymer composite dough which was stencil-printed on an elastomer substrate to form stretchable conductors (Journal of Materials Chemistry C, 2016, 4, 4150−4154, DOI:10.1039/C6TC01052K).

Then, we synthesised two types of self-healing polyborosiloxane elastomer nanocomposites containing different conductive carbon nanofillers (including graphene nanosheets) and investigated their structure and properties. One of them formed flexible electronics with a common elastomer substrate which showed excellent mechanically and electrically self-healing properties, as well as strong adhesion to the elastomer substrate (ACS Applied Materials & Interfaces, 2016, 8, 24071−24078, DOI: 10.1021/acsami.6b06137). The other also demonstrated excellent properties and was studied as sensors (Paper Submitted).

Meanwhile, we synthesised self-healing, conductive fatty acid elastomer nanocomposites with piezoresistive effect for pressure sensing (RSC Advances, 2017, 7, 20422−20429, DOI: 10.1039/C6RA28010B).

Finally, we developed new facile methods to fabricating stretchable and porous conductors (Scientific Reports, 2017, 7, Article No. 17470, DOI: 10.1038/s41598-017-17647-w) as well as highly conductive, highly stretchable and stable conductors (ACS Applied Materials & Interfaces, 2017, 9, 43239−43249. DOI: 10.1021/acsami.7b08866) based on elastomers and carbon nanofillers for applications including sensors and wearable medical devices.

In total, we produced 6 journal papers (5 published and 1 submitted) from this project, and also disseminated our research findings at conferences, open-access repositories, project website, etc.
Four types of new self-healing, conductive polymer nanocomposites based on different polymers and different carbon fillers (including graphene nanosheets) were prepared and investigated as stretchable/flexible conductors with self-healing capability. In addition, two new low-cost fabrication methods were also developed for the manufacture of stretchable conductors.

Potential impacts
This project will have potential academic, economic and societal impacts. It will bring new knowledge to the areas of polymer nanocomposites, carbon nanomaterials, “smart” materials and stretchable electronics, whilst also providing advanced materials for further research and development of next-generation stretchable devices. In the longer term, the new materials developed from this project will benefit patients who need to wear medical devices as well as the materials, manufacturing, energy and healthcare sectors.

Impacts so far
This research has resulted in five peer-reviewed papers in highly rated materials journals so far (with another one to be published), with the goal to generate science at the high level and achieve the wider readership and academic impact. The participation in the Pilot Scheme on Open Research Data in Horizon 2020 has helped maximise access to and re-use of the research data generated from the project, which has enhanced the impact of the project so far. Furthermore, the research findings from this project have also been disseminated through conference presentations, lectures, project website, etc. These activities have helped researchers in the field, students and the public gain access to the research findings of the project and better understand the research topic. The project has also helped the MSCA Research Fellow to secure an independent academic career towards the end of the project.
Figure 2 showing a self-healing flexible conductor based on a conductive elastomer nanocomposite
Figure 1 showing a stretchable and flexible conductor based on a self-healing conductive composite